One of the lesser known cases in ufology here. The little town of St. Helens, Oregon, spring of 1981. Around 4am officer Rusty Yokum was on patrol
when he saw a bright, gleaming object flying directly above the nearby Columbia River (he was driving on the highway that runs directly West of
it).
He happened to have a tape recorder, and got audio of the sounds the UFO was making, along with the descriptions made by other officers who gathered
from a higher bluff to observe the apparent craft. Portland Airport initially told them they tracked an anomalous object above the river, but then
called Yokum back, saying they found nothing and to stop looking into it.
J. Allen Hynek reviewed the case and called it a "total puzzle," and a review of the audio found the sounds (occurring in three distinct frequencies,
as seen in video) don't occur in nature.
Source is the declassified tape itself and initial interviews made by the officers.
I was a deck hand on a cruise ship that sailed up and down that river -- as well and the Snake River, back in 2015. For about 3/4's of my time spent
working aboard that ship, i typically had the 'graveyard' shift, 10pm - 10am, and was almost always at the helm alongside the Captain.
When i wasn't steering the ship, i would provide visual support.
There were a couple time's where i wasn't the only one who was witnessing what we did.
Coast Guard has a strong presence in the area, especially regarding Astoria.
Kind of made me think of the cash Landrum case! Just checked and they claim they heard a rushing sound "like a flame thrower" when the object spewed
out flames.